Inside Knowledge: Dehumidification Equipment
Pools make for challenging construction in outside installations, but they become increasingly complex as you bring them indoors. You not only have to be concerned about the pool system, you now have to address issues like dehumidification, water and space temperatures and higher operating costs. "Inside knowledge" can go a long way in facility construction and dehumidification equipment choices.
The main issue is, of course, what to do with the water vapor that forms over a pool in an enclosed space. As moisture fills the structure, damage can occur and in general the environment becomes uncomfortable for occupants. Before the advent of modern dehumidification systems, doors and windows were left open, providing minor relief from the humidity. Fans were later added to help draw out moisture and maintain a balance, but this method also proved only marginally effective, especially in colder climates where heating was required.
Today's dehumidification systems have come a long way since then and are designed specifically for the corrosive indoor pool setting. They not only manage moisture, they recycle energy, maintain tight temperature setpoints and can offer instant performance and maintenance details from any location with access to the internet. It's important, however, to understand the indoor environment and how dehumidification equipment functions to get the best performance from your system.
Factors In Harmony
There is an ongoing relationship between internal and external temperatures, humidity level, structure type, ventilation, pool water chemistry and equipment. When all are working in harmony, the facility will provide a comfortable, healthy environment that is cost effective to operate. When the variables begin to change, comfort, operating cost and/or maintenance can suffer greatly.
Water/air temperatures and humidity levels must be within a narrow range for occupant comfort. Ideal water temperature is around 82 degrees with the air temperature slightly higher to prevent chilling once exiting the pool. The desirable humidity range is generally 50 percent to 60 percent. Anything greater than 60 percent creates a sticky feeling and/or difficult breathing, and low humidity results in evaporative cooling on the bather's skin, resulting in a chill. Athletic pools hosting swim meets generally operate with cooler water/air temperatures and health/therapy facilities tend to have higher water/air temperatures.
The poolroom environment is in a constant state of flux as internal and external variables change from season to season. Outside temperatures affect the inside heat loss/gain sometimes, resulting in the need for more energy to maintain occupant comfort. For a majority of indoor pools, regardless of geographic location, water and space heating are required 70 percent to 90 percent of the year.
Indoor pool designers and contractors need to control and balance five crucial variables that include indoor air quality (IAQ), occupant comfort, energy cost, pool water chemistry and asset protection. The interrelationship between the variables is complex, and changing one or more may affect the others. Small variations in the pool environment may result in discomfort; large imbalances in the pool environment can result in very high operating cost, destruction of equipment and structure and even occupant injury.
Management of the rate of evaporation is an important aspect of indoor pool environment care. At a base level, it is a function of water temperature — the higher the water temperature, the greater the evaporation rate. That evaporation rate is also influenced by the difference in temperature between the water and air, and the greater the difference between the warm water and the cooler air above it, the greater the rate.
The rate of evaporation is also a function of the water surface area, a concept that also applies to the tremendous increases in water surface area due to agitation from pool activity, water slides and implements such as water cannons. The splashing water increases the effective surface area thereby increasing the evaporation rate within the pool structure.
Another important fact to keep in mind in this discussion is evaporation removes heat from the water, which causes it to cool. To maintain water comfort conditions, additional energy is needed to overcome evaporative heat loss and sustain the water's original set points.
So where does all this evaporated water — this moist air — go? If not removed through ventilation or mechanical dehumidification, it will condense on any cold surface it touches. In most cases, this condensate includes chloramines, a corrosive byproduct of the pool's sanitization process, that aggressively attack metallic surfaces including furniture, fixtures and structural components.
There are confirmed incidents where corrosive moisture has leached into precast concrete roof structures, corroding the rebar, resulting in collapse and injury. A little known fact is that chloramines in the saturated air also attack and discolor most common stainless steels creating "stress corrosion," which can lead to structural failure. That's why it's critical to constantly maintain correct pool chemistry — keeping chloramines under control — along with the proper relative humidity.
The Pool-Spa Operator's Handbook recommends chloramine levels not exceed 0.2 ppm. Above that level, the corrosion process caused by the chloramines in the air accelerates. It's important to note that chlorine odor is often blamed on poorly functioning dehumidification units but in reality is the result of improper pool chemistry. Dehumidification equipment can help dilute the odor through ventilation but will not fix the problem. High levels of chloramines over prolonged periods will not only affect the pool facility (not to mention bathers), but it can also cause severe damage to the dehumidification unit.
Dehumidifiers using mechanical refrigeration are very efficient and control temperature and humidity effectively in all size swimming pools.
Courtesy of Pool Pak
Dehumidification Systems and How They Work
For ease of discussion, dehumidification systems can be divided into two major types: those using mechanical refrigeration to remove moisture and ventilation-based systems using dryer outside air and having no refrigeration components. There are advantages and disadvantages to each system, and your choice will depend on initial cost, operating cost, maintenance, level of desired control and location.
Pool dehumidification systems using mechanical refrigeration, often referred to as Direct Expansion (DX) systems, are the most popular. They are probably the most common dehumidification systems used for small to medium pool room applications due to their tight control of the space temperature as well as overall good life cycle cost. Heat and moisture are removed the same way an air conditioning system does it, with the major difference being the way the system reuses the recovered heat.
In all DX systems, refrigerant vapor flows through the compressor, raising its temperature and pressure. The refrigerant then flows through the condenser, where it condenses to a liquid, giving off heat in the process. The refrigerant next goes through the expansion valve, where it experiences a pressure drop before going to the evaporator, where it absorbs heat, causing the refrigerant to vaporize again and in this state it returns to the start of the cycle. This last phase, where heat energy is drawn from the surrounding air, is the desired effect and the part we're paying for. As this happens — as the warm, moist pool air flows over the cold evaporator coil, moisture condenses and drains away while the air is cooled.
In a conventional air conditioning system, the heat generated during the compression cycle is normally discharged to the surrounding outdoor environment. Dehumidification systems for pools, however, are designed as heat pumps, using the waste energy to heat the pool water and/or air. The recycled energy in many cases can satisfy up to 90 percent of the pool's heating requirements A process called hot gas reheat is used to reclaim the heat energy, and that simply means the heat removed from the warm, moist air as it enters the dehumidifier is added back to the air as it passes through the unit. The result is the warm, moist is converted into warm dry air as it leaves the dehumidifier and returned back to the pool to start the cycle again. The moisture is likewise removed during the air cooling process in the form of condensation.
The benefit of this approach is the high Coefficient of Performance (COP). Efficient dehumidifiers have a COP around 5, which simply means five units of "heat energy" is produced for every unit of electricity used. This heat energy is then used to heat space or the pool water.
Packaged dehumidification equipment built for pools incorporates more sophisticated mechanical design and software than conventional air handling systems, and this helps to minimize operating cost. Initial cost for these systems is higher than ventilation systems because of the added refrigeration components, but the cost of operation decreases over time because less supplemental heating energy is needed. They do require periodic HVAC maintenance and a certain level of knowledge to operate, but the added benefits can easily outweigh the extra cost.
DX dehumidification systems offer very precise facility temperature and humidity control during all seasons for maximum occupant comfort. They will operate in any geographic area, including the hot, moist Southeast and can offer cooling by adding an outdoor condenser.
Using Outside Air for Moisture Control
Dehumidification can also be effectively managed using ventilation to remove excess moisture. This is accomplished through dilution with outside air, and is a brute force approach to dehumidification under the premise that enough drier, outside air will offset the effects of pool evaporation. This system has no self-contained means of cooling during the hot summer season, especially when the temperature difference between outside and inside is minimal, although a chilled water coil can be incorporated from an external system.
Packaged outside air systems can be equipped with a furnace to maintain air and water temperatures or they can rely on external auxiliary heaters. For energy efficiency, using an air-to-air heat exchanger in the supply and exhaust air steams can reduce fossil fuel heating by up to 50 percent.
Capital cost is lower for a packaged ventilation system compared to mechanical refrigeration systems, and the technology requires less technical personnel for maintenance. Temperature and humidity control are not very good with a ±30 percent variation during the summer season.
Dehumidifiers that use mechanical refrigeration also use outside air to remove moisture, but to a much lesser degree. Ventilation is required to meet IAQ requirements, and compressors can be shut down during non-peak hours and evenings when outside conditions permit to save on energy usage.
Vapor barriers must be installed at the interior surface to prevent moisture migration into the wall structure where it condenses in the insulation once it reaches the dew point temperature.
Good Facility Construction Practices Increase Efficiency
Choosing the right dehumidifier for your pool is only part of the equation when designing an efficient indoor pool enclosure. Approved construction techniques save energy, reduce condensation and improve comfort.
The objective of an air distribution system within a high moisture environment is to maximize flow of warm, dry supply air over any surface that is prone to condensing temperatures, including all walls, windows and skylights.
A ceiling supply arrangement should be located near the windows, preferably close enough to sufficiently wash the cold glass with an even blanket of air. Up to 80 percent of the supply air should be directed at the walls and windows. Washing the walls with warm, dry air reduces the incidence of cool, dead air spaces that may form around windows or walls and migrate to the pools edge.
The remaining 20 percent of the supply air should be directed along the ceiling to break up any stratification and stagnation occurring near the ceiling. For low-set windows and sliding glass doors, the supply air should be ducted below grade around the inside perimeter of the enclosure using corrosion-resistant PVC piping and linear slot diffusers.
Return inlets should be located to allow efficient flow of the moist, warm air back to the dehumidification unit. This not only increases dehumidification efficiency, it also eliminates dead areas where air stagnation can occur.
Traditionally, return duct heights have been about 10 to 15 feet above the floor, but it has been found that chloramine-saturated air blankets the pool surface and does not adequately re-circulate through the dehumidification system. The result is poor indoor air quality that poses a health risk for the pool occupants. A better strategy is to position return(s) near the surface to lightly draw off the chloramine layer and moist air while not dramatically altering the evaporation rate or creating uncomfortable air currents.
Return and supply ducts should never be positioned as to allow short cycling of the supply air. Short cycling occurs when supply air is released too close to the return duct causing it to prematurely return to the dehumidifier before it is able to circulate in the space.
Another important consideration is to maintain negative air pressure in the pool area relative to the surrounding spaces within the same building. The negative pressure prevents both moisture and chlorine odors from drifting into other areas of the building.
Moisture Barriers Prevent Moisture Migration
Moisture migrates from a space with a high humidity ratio to a space that has a lower humidity ratio. It migrates through most building materials, and can cause condensation on building surfaces and leach into concrete walls.
As moisture migrates through walls, it will impregnate the insulation and condense as the outside temperature drops and the dew point is reached. This will result in a decrease in R-value from the wet insulation and even a loss of structural integrity.
At the very least, vapor barriers should be installed immediately behind the interior wall surface facing outside, but a more comprehensive approach is to protect all natatorium walls, ceiling and flooring to totally isolate the moisture.
In addition to the inside walls, exterior walls of the natatorium must be built so infiltration of outside air will be blocked near the outside surfaces of the enclosed space. A vapor membrane at a warm-wet inside surface blocks infiltration, but local condensation will occur if cold infiltrating outside air contacts this boundary. Vapor membranes and infiltration barriers must be completely sealed or condensation can occur at or near leakage points.
Good thermal performance doors and windows exposed to outside air limit heat migration and condensation formation. Double and triple glass panels are best and they should be insulated or sealed in metal or vinyl clad frames wherever possible. Window frames must have thermal breaks and be sealed to adjacent walls and insulated with a non-porous insulating material.
Building and maintaining an indoor pool facility is a major undertaking, and it must operate efficiently to maximize the return on investment. By selecting a packaged dehumidification system designed for your unique location, you can be assured of maximizing user comfort, protecting assets and reducing maintenance to the lowest possible cost.
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World's Largest Swimming Pool Photos Are Amazing
from Huffington Post
It's not often that a photo causes an audible reaction, but these pictures of the world's largest swimming pool are most definitely whine-worthy.
We told you about this glorious man-made pool that sits on the grounds of the San Alfonso del Mar Resort in Chile last year, but when we stumbled upon new photos of this piece of perfection, we couldn't resist a revisit. So, for your mid-Monday blues, we offer this brief peek into paradise. Enjoy!
Have you come across any pools that have made you consider a life aquatic? If so, tweet them to us at @HuffPostTravel.
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AI Air Bags For Water Safety
Inventors dream about new technologies or new applications that could make the world more comfortable or safer. The dream is the most important part, because often the step between a dream and a new product is a small one.
With that in mind, some technological dreamers are imagining systems that could prevent drowning even when no lifeguards are around.
Computer-based imaging systems at swimming pools already alert lifeguards when a body is underwater too long, but these systems are still rare and they do not work in natural bodies of water.
New Scientist magazine reports that Ken Sakamura and his colleagues at the University of Tokyo have created an Artificial Intelligence system that can sense the jerking, flailing movements of a swimmer in trouble. The system contains pressure sensors that detect the waves that pass through water as the result of a swimmer's movements. Software in the system identifies these pressure wave profiles and distinguishes normal from distressed movement.
The system could be used to trigger a body-worn floatation bag, which would provide buoyancy automatically to a floundering swimmer. The team from Tokyo presented their ideas at the International Conference on Consumer Electronics in Las Vegas, Nevada, on January 12.
Swimming Pool Heat Pump: Pool Heaters 101
Unless you live in a very warm climate, heating your swimming pool at certain times of the year is necessary to keep swimmers comfortable and maximize enjoyment. Over the next few posts we will be featuring a mini-blog series discussing all the different types of swimming pool heaters, today we will talk about a swimming pool heat pump.
When it comes to heating your swimming pool, a pool heat pump is an incredibly environmentally friendly and efficient way to do it. Heat pumps are cost-effective, eco-friendly, reliable, energy efficient, and speedy.
What is a Swimming Pool Heat Pump?
A pool heat pump, is a swimming pool heater that absorbs heat from the air surrounding the unit and transfers that heat into your pool water. Heat pumps are sometimes considered a cross between a solar heater and an electric heater.
How does a pool heat pump work?
Pool Heat Pumps are powered by electricity but as the sun heats the air around the heat pump it is able to absorb that heat and transfer it to the pool water. Though powered by electricity, heat pumps actually run on very little electricity making them a very inviting choice for pool owners who want to keep things as "green" as possible. The only swimming pool heater that is better for the environment is a solar heater but you may find those to be far less efficient.
Benefits of a Pool Heat Pump
Not only are they environmentally friendly, swimming pool heat pumps are also very cost effective. Though the initial cost may be more when comparing to a gas or electric heater, the cost to operate a swimming pool heat pump and the energy savings it provides will quickly payoff.
Most pool owners who use a heat pump find that they are very reliable and easy to use. At Sunplay, we carry UltraTemp Heat Pumps by Pentair. The Pentair UltraTemp Heat Pumps come standard with an AutoSet feature that continuously monitors water temperature and turns the pump on and off as needed to maintain optimum water temperature while conserving energy. The UltraTemp's also feature a titanium heat exchanger that assures corrosion free performance for added life and value.
If you are looking for a cost-effective, energy efficient, reliable pool heat pump, a UltraTemp Heat Pump from Sunplay may be just right for you!
Once an afterthought at best, gate and fence treatments have become key elements in the finely crafted projects of Phoenix-area designer/builder Roger Soares, owner of Hydroscapes, a firm specializing in highly customized aquatic environments. Here he demonstrates in words and images just how dynamic and important these peripheral structures can be when treated with care and creativity.
In our work designing and building pools, spas and other aquatic features, it can be easy to focus entirely on what's happening inside the property lines. In our work at Hydroscapes (Scottsdale, Ariz.), we've discovered there's tremendous value in considering the structures that define the boundaries of the space and provide points of entry.
Specifically, we've learned through years of design exploration and first-hand experience that designing and building custom gates and fences can present a tremendous opportunity to add creative and functional elements to a project – if you take the time to step back and look at these structures through fresh eyes.
Certainly, in many situations, the fences and gates already exist and the client may not have any need or interest in changing them. In our work, however, we've found numerous situations where gate and fence treatments become an extremely important part of the overall design scheme and become a point of tremendous interest and enthusiasm for the client.
For example, when the pool area is located in a front yard (something we see more and more of these days) the gates and fences involve a range of critical issues including the appearance of the property's frontage and the ability to block and reveal views of the pool area, not to mention defining the initial experience of entering the property.
In other situations where you have large properties, gates and fences can be used to define the pool area within the property. And there are many situations where clients realize it only makes sense to do something creative or stylish on the perimeter as a way to accentuate the work being done within their yards. If safety is a concern, for example, why not make those barriers as attractive as possible rather than consigning yourself to the notion that fences present some sort of visual compromise.
Overall, it's fair to say that gate and fence work represents an opportunity to add tremendous visual interest to a property, yet it's something that many people in our industry barely consider or even completely ignore. I think that's a mistake because when you step back and think about it, these are tremendously important structures that define access, frame views, can make dramatic or subtle stylistic statements, define visual boundaries and, of course, add measures of safety and security depending on the situation.
Years ago, we started working with fence treatments due to our clients' maintenance concerns. Here in Arizona's Valley of the Sun, the elements can be extremely tough on certain materials, such as the wood used in many common types of fencing. We started designing fences using metal as a way to relieve those issues and to give the clients something more visually interesting compared to an ordinary plank or picket fence.
With that modest start, it wasn't long before we became more and more involved in gates and fences from a far more ambitious design standpoint. These days it's something we bring up with the vast majority of our clients and we've found that they often become extremely excited knowing that they're going to have something beautiful to look at.
It's become another element we can use to give the clients something no one else has.
What's so neat about these kinds of additional features is seeing how the outcome plays out with each client. Oftentimes, doing something creative with a fence or gate adds very little, if any, cost to the project. It's simply a matter of looking for alternative materials or design treatments. If you're building a large masonry wall finished in stucco, for example, the wall has to be some kind of color, so why not make use of the color palette you're already using on the project? Or perhaps finish different sections of the wall in different colors to add interest, or use different textures in various places to create visual variety.
By simply varying texture and color on these vertical elements, you gain a wide range of design options that can be used in all sorts of interesting ways and, again, often with very little or even no impact on budget.
On the other end of the spectrum, there are situations where clients will opt for expensive treatments that become spectacular design elements. For example, we've worked with various metal and glass craftsmen who collaborate on intricate designs that become works of art themselves.
We've done large wooden gates that have windows and various types of apertures that serve the dual purpose of making a powerful aesthetic statement while also giving visitors glimpses of the garden spaces on the other side. We've created custom gate designs that are sculptural in nature and impress visitors from the moment they approach the property.
When such clients want their doors or gates to make a statement, to have them stand out amongst their neighbors, it becomes an extremely exciting part of the discussion. In many cases, it's because they've seen other treatments that impress them and they want the same thing for themselves. Oftentimes, we amplify that excitement by showing them designs we've done in our own work and in many of the places we seen throughout our travels.
It's one of those tangential discussions that can become as interesting and dynamic as any other element of the project.
In many settings, transparent fence and gate treatments can be used to both frame the space with stylistic elements, and minimize visual distractions.
POWER OF INFLUENCE
Without question, travel and research into design traditions can pay tremendous dividends as you develop concepts for use in projects. As one smallish example, my wife, Sheri, and I recently visited New Orleans for the 2012 PSP show. We took time out to tour the legendary Garden District, a neighborhood chock full of beautiful homes designed in an array of great traditions such as antebellum, French provincial, Greek revival, Italianate and Victorian, among others.
The tree-lined streets are like a living design museum. Common to many of these spectacular homes are fences and gates that define the properties' frontages. You can partially see beyond the property line into all sorts of beautiful gardens and courtyards. Some of these gate and fencing designs are extremely simple, other far more elaborate, but in almost all cases they entice you to stop and peek into the property. It's all part of this fantastic pageant where you're separated from the homes while at the same time visually invited to stop and take in the highly personalized landscapes and magnificent architecture.
Another huge and entirely different set of examples can be found in the traditions of Asian design. I'm a huge fan of Japanese design and greatly admire Japanese architecture and landscaping. One of the hallmarks of that ancient design tradition is the use of fences and gates to partially conceal and reveal garden spaces, to provide a sense of discovery as you move through the landscape. The structures themselves are often rendered with simple, yet beautiful wooden structures that both contrast and yet seamlessly blend with natural forms.
Chinese design, on the other hand, is much different. There you tend to find fences and gates used as imposing barriers where there is a far more pronounced feeling of separation within the landscape. These structures can be beautiful in their own ways, no question, but they are also often quite monolithic and imposing.
Although I personally prefer the more seductive approach found in Japanese design, there are useful lessons to be gleaned from both traditions in that they demonstrate how the structures that both prevent and provide access can tell you something about the people on the other side.
And, of course, there are almost infinite examples of vastly differing design styles to be found throughout Europe. From the great Italian villas to French gardens and the Moorish designs of Spain, as you travel and actively pay attention to the structures and their detailing, you can find volumes of different ideas that can be repurposed in our work back at home.
Here a beautifully simple gate frames both the entrance to this contemporary yard and the stunning distant mountain vista.
Even if you don't specifically use design details from those types of explorations, the principles used in the modalities of great design can still be applied on conceptual basis. A prime example would be the conceal/reveal techniques in Japanese design. Regardless of the stylistic palette, you can always apply the concept as a way to generate interest, even mystery in the work through transparent elements such latticework, windows or apertures.
In the greater Phoenix area, where we do the majority of our projects, we're often working in either contemporary or Spanish colonial settings, which you can see in the images on these pages.
Everything I've said above applies to those projects and hopefully you can see the numerous ways that the gate and fence treatments are used to introduce, frame and elaborate on the various design programs within the properties.
In some cases, you'll see how we've used fencing structures to open up views to the dramatic surroundings of the Sonora Desert with the use of highly transparent structures. In other situations, we've used monolithic walls to conceal unwanted views and create areas that feel extremely private and intimate. In other situations, we've used combinations of the two to generate variety and spatial definition between different areas within the landscape.
Likewise, the gates cover a variety of concepts, some being magnificent works of architectural art that make bold statements about the homeowners' tastes, and in other, the gates are far subtler, and all sorts of designs that fall somewhere between those two extremes.
Across the boards, these gates and fences are all designed and built to add value to the setting and serve as surprising points of pride for our clients. All in all, working creatively with these peripheral features is a great way to step outside the proverbial box.